The present application relates to internal combustion engines and methods of operation thereof. More specifically, the invention relates to 4 cycle engines with spark or compression ignition, that are capable of completing 4 cycles in one revolution of the crankshaft and having automatic opening of the intake and exhaust ports.
There are two factors that have been important in determining the direction of development of the internal combustion engine. The first factor is the increasing cost of fuel due to a global shortage. The second is the necessity to reduce pollution into the atmosphere.
There have been two main thrusts in the recent development of the internal combustion engine. The first development has been in engine fuel ignition and gas control management where electronic computers that sense engine parameters have been employed. The sensed parameters are used to calculate necessary fuel injection rates and fuel is supplied at the proper rate and ignition is advanced or retarded as required. This computerized fuel and ignition control system has been very successful in reducing pollution and increasing fuel efficiency.
The second development thrust has been in mechanical improvements. The need to improve volumetric efficiency or breathing has resulted in engines having four valves per cylinder head, turbo charging, variable opening valves, variable intake valve throttles and fuel injection directly to the cylinders or indirectly through the manifold. This has lead to greater mechanical complexity and the attendant higher manufacturing costs.
There are mechanical limitations to efficient engine management. Examples are the restriction in high speed operation due to valve bounce and limiting sympathetic crankshaft vibration.
A further example of an inherent mechanical restriction is apparent from the scavenging process. In a four valve per head engine, as the valves become larger they become closer, permitting the intake charge to flow directly from the intake valve, to the exhaust valve and port, without driving the remaining exhaust gases out. Also, some of the intake gases will flow into the exhaust port and then back into the cylinder during the intake stroke but this is erratic and unpredictable.
Another mechanical limitation results in poor flame front propagation. In a piston cylinder engine, the gas is ignited at the top of the cylinder and the piston is retreating from the flame front. It is known that if charged gases are pushed toward the flame front, substantially better and more complete combustion would be possible.
If the number of cylinders could be reduced, the engine could be lighter and smaller with a shorter crankshaft. If lower speed operation and higher R.P.M.""s were possible, engine flexibility would be improved and a lower number of transmission gear ratios would be required for engines in vehicles, this in turn would lead to lower weights and better economy.
Dynamic unbalance in an engine can be eliminated by a balance shaft running at two times engine speed but this causes additional mechanical cost and mechanical complexity. If a single chamber engine is in balance this balancing would make possible all types of engine arrangements such as V, inline and radial and with any number of cylinders.
An ideal engine should have the simplicity of a two cycle engine with self opening ports and with the ability to run at high speed, requiring only one revolution per power stroke, this would reduce the number of chambers required and also eliminate the need for valves, valve springs, lifters, rocker arms, camshaft, reduction gears, chain drive and separate cylinder head and gasket. This simplified engine should not require lubrication of the chamber walls internally by adding lubrication to the intake gas charge entering the cylinder chambers as in a two cycle engine as this lubricant is consumed and it will cause pollution.
An improved engine arrangement will have the hot exhaust valves and port areas away from the intake and compression areas this will prevent preignition therein permitting higher compression ratios that will give better thermal efficiency and that will lower fuel costs and contribute to reduced pollutions.
It is therefore a main object of the present invention that this engine will complete four cycles, intake, compression, expansion and exhaust in one revolution of the crankshaft, that this will require only half the number of cylinders for an equal number of power pulses per revolution, which will reduce weight, size and length. This reduction in length will also reduce the crankshaft length and improve the crankshaft torsional stiffness.
A further related object is to provide an engine that will not require mechanically operated valves, this engine will have intake and exhaust ports that are covered and uncovered by the gas control chamber members and the engine will have four ports, two opposed intake ports and two opposed exhaust ports that are on opposite fixed walls of the gas chamber and are utilized to sweep the exhaust gases from the exhaust chamber during the overlap period of exhaust and intake openings.
An object of the present invention is to eliminate valves, springs, lifters, rocker arms, tappets, camshaft, camshaft bearings, reduction gears for the camshaft and a timing belt required by a conventional four cycle piston engine.
A related object will be to eliminate the head to block joining and gasketing problems.
It is a further object of this invention that each individual gas control chamber of this engine will be in primary dynamic balance using a crankshaft counterweight, this will permit different engine configurations such as xe2x80x9cVxe2x80x9d, flat and inline with varying number of cylinders.
Yet another object of this invention is to eliminate the two major detriments to high speed engine operation in a conventional four cycle piston engine, the first being valve bounce and the second is limiting sympathetic crankshaft vibration.
A further related object is to provide an engine that will be more efficient having a potential for higher compression ratios and having more consistent and less erratic flame front travel and that this will translate into a less polluting engine by having a gas control chamber that will move the gas into the flame front, this will promote faster and better combustion and additionally reduce knock that results from poor end gas combustion.
A related object will be to remove the intake and compression strokes from the hot exhaust port area to permit a higher compression ratio with the same octane fuel and this will translate directly into higher thermal efficiency and reduced exhaust emissions.
A further object is to scavenge the engine gas chambers during the overlap of the exhaust and the start of the intake stroke accomplished by delaying the fuel injection during this initial period when the intake gases are flushing out the exhaust gases.
A further object is to produce good squish action that will direct opposed jets of gas towards each other in the gas control chamber to promote swirl and turbulence of the fuel mixture for more complete combustion.
It is a further object of this invention that the volume to surface area ratio will be similar to a conventional four cycle engine, and the gas control chamber will have no sharp recurvate angles, to quench the flame front.
Another object of the present invention is to provide a ratio of port area to valve area that is similar to a four valve per cylinder conventional piston engine.
A further object is to provide gas sealing that is similar to a conventional engine with groove seals using gas pressure to force the seal against the sealing surface and the side of the groove and with an oil control ring to scrape and wipe excess oil from the moving sealing surfaces to reduce oil consumption while still providing adequate lubrication.
It is yet another object to provide an engine that will be operational dimensionally stable, that can be made larger or smaller and operate in a manner similar to large and small four cycle conventional piston engine.
It is a further related object that this invention can be operated as a diesel engine with compression ratios of 23:1 or higher and with compression ignition, while still maintaining an adequate bearing area.
Another object is to provide an engine that will be substantially lower in manufacturing cost than a conventional four cycle piston engine.
Other objects and advantages of this invention will become apparent from a consideration of the following specifications and drawings. Before proceeding with a detailed description of the invention, however, a brief description of it will be presented.
A first embodiment of the invention that will be described is an improvement of the four cycle internal combustion engine, the engine described will be a two chamber engine, for simplicity the operation of one chamber is described. The engine will have a four sided gas control chamber operating between two fixed parallel containing walls with opposite sides of this gas control chamber parallel and with opposite sides equal in length between their four commonly hinge pin ends and with the vanes equal in width and contained and slidable between two parallel walls that are spaced apart the width of these vanes. The vanes having flanges parallel to the containing walls to provide a surface for sealing of the gas control chamber and to transfer the heat of combustion to the parallel side containing walls. With the two adjacent vanes that are on either side of the extended main hinge pin and that are driven having bearings that are parallel to the hinge pins that are used to locate the wrist pins. The parallelogram of vanes free to rotate and translate about the extended main pin that is perpendicular to and located by the closing side walls.
This gas control chamber will be operated by a crankshaft the axis of which is perpendicular to the parallel fixed side wall, and free to rotate in bearings fixed by the side containing walls and with a crankpin bearing located between the containing wall that will have two rotatable side by side connecting rods that will drive the two driven vanes of the gas control chamber through a wrist pin located at the opposite end of the connecting rods these commonly connected to each other by the main crankpin and being restricted to rotary motion by this extended main pin. The wristpin will be displaced from the main hinge pin at a distance so the rotation of the crankshaft will rotate the crankpin and impart a driving motion to the wrist pin through the connecting rod to rotate these two driven vanes, that will in turn rotate and translate the opposite two follower vanes about their common hinge pin so that they are driven in translation and rotation that will cause the parallelogram gas control chamber to lozenge and close across alternate corners and this then will cause the volume to be reduced to a minimum for maximum compression when the crankpin is at top dead center. The crankshaft will continue to rotate towards bottom dead center to pass through a maximum expansion and the gas control chamber will be reduced in volume to a fixed minimum compression ratio for the completion of the exhaust and the start of the intake that occurs at bottom dead center. The crankshaft rotation will continue through bottom dead center and when the gas control chamber hinge pin axis are at a right angle with the gas control chamber at maximum volume and this will end the intake stroke. The compression stroke that follows will be completed when the crankpin is at top dead center, at this time ignition will occur and the 4 cycles will be repeated again.
Another aspect of this invention is the operation of the intake and exhaust ports, these ports are located adjacent to the main hinge pin in the side containing wall and behind the flanges of the wristpin driven vanes of the gas control chamber and will be opened and closed at the appropriate time in the following manner, as the crankshaft rotates past top dead center and ignition of the compressed charge occurs and when expansion is almost complete, the vane that is driven on the side of the gas control chamber that covers the exhaust port will be uncovered and start to open due to the rotation of this driven vane and as the crankshaft rotates and approaches bottom dead center, the crankpin motion will be generally side to side and this side to side oscillation about the main hinge pin rotating about the main hinge pin will be transmitted and will rock the whole gas control chamber so as to keep the vane on the intake side closed until bottom dead center is reached then the mostly side to side motion of the crankpin will rotate the gas control chamber rapidly causing the intake port to be uncovered and the exhaust port to close and as the crankpin continues to rotate through the next quadrant the motion will rotate the driven vane assembly causing the intake to close and the compression portion of the cycle to begin, ending with the crankshaft at top dead center once again, to begin again the four cycles required for a four stroke internal combustion engine.
Another aspect of this engine, is that it can be substantially balanced for both the reciprocating and oscillating motion of the center of mass of the gas control chamber and the side by side rotary rocking of the gas control chamber. It can be seen that the center of mass of the vanes of the gas control chamber is rotating counter to the counter weight rotation diametrically opposite the crankpin and this constitutes a couple about the mass of the engine that will cancel.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings.